Apparatus and a method of feature edge extraction from a triangular mesh model

Abstract

A feature edge extraction technique supports automatic creation of a solid model from a 3D or triangular mesh model. The technique extracts feature edges from the 3D mesh model according to a global normal-line evaluation method and an improved watershed method. The technique uses data related to the 3D mesh model, defines an area with a Euclidean distance, globally evaluates normals of triangles in the area, calculates edge and vertex feature values, carries out discretization and differentiation on the calculated vertex feature values, extracts feature edges satisfying requirements, divides the mesh model into segments each consisting of connected triangles according to the improved watershed method that is capable of grouping vertexes, extracts the boundaries of each segment as feature edges, allows a user to interactively select required feature edges from among the extracted feature edges, and outputs data related to the selected feature edges.

1 . An apparatus for extracting feature edges from a triangular mesh model, comprising; 
 a storage unit configured to store data;    a vertex feature value calculator configured to retrieve data related to the mesh model from the storage unit, globally evaluate normals of triangles in each region that is defined on the mesh model by a Euclidean distance, calculate edge and vertex feature values based on a result of the evaluation, carry out discretization and differentiation on the calculated vertex feature values, and extract feature edges;    a segmentation unit configured to separate the mesh model into segments each composed of a set of connected triangles according to the calculated feature values and an improved watershed method capable of grouping vertexes and extract boundaries of the segments as feature edges; and    a feature edge selective extractor configured to allow a user to interactively select required feature edges from among the extracted feature edges and output data related to the selected feature edges.    
   
   
       2 . A program for extracting feature edges from a triangular mesh model, the program instructing a computer to execute the steps of: 
 retrieving data related to the mesh model from an input unit or a storage unit;    globally evaluating normals of triangles in each region that is defined on the mesh model by a Euclidean distance and calculating edge and vertex feature values according to a result of the evaluation;    carrying out discretization and differentiation on the calculated vertex feature values and extracting feature edges;    separating the mesh model into segments each composed of a set of connected triangles according to the calculated vertex feature values and an improved watershed method capable of grouping vertexes, and extracting boundaries of the segments as feature edges; and    allowing a user to interactively select required feature edges from among the extracted feature edges and outputting data related to the selected feature edges.    
   
   
       3 . The program of  claim 2 , wherein the program further instructs the computer to execute the steps of: 
 setting extraction parameters and the number of times of repetition; and    repeating the steps with the use of the set extraction parameters for the set number of times of repetition.    
   
   
       4 . A method of extracting feature edges from a triangular mesh model, comprising the steps of: 
 retrieving data related to the mesh model from an input unit or a storage unit;    globally evaluating normals of triangles in each region that is defined on the mesh model by a Euclidean distance and calculating edge and vertex feature values according to a result of the evaluation;    carrying out discretization and differentiation on the calculated vertex feature values and extracting feature edges;    separating the mesh model into segments each composed of a set of connected triangles according to the calculated vertex feature values and an improved watershed method capable of grouping vertexes, and extracting boundaries of the segments as feature edges: and    allowing a user to interactively select required feature edges from among the extracted feature edges and outputting data related to the selected feature edges.    
   
   
       5 . The method of  claim 4  further comprising the steps of: 
 setting extraction parameters and the number of times of repetition; and    repeating the steps with the use of the set extraction parameters for the set number of times of repetition.